This invention relates to an apparatus for surface treating workpieces such as vehicle bodies by immersing them into a treatment bath for performing a surface treatment such as chemical treatment, electrodeposition or the like.
An apparatus of this type is disclosed in Japanese Published Unexamined Patent Application No. 229167/1988. The apparatus includes a jig for holding a vehicle body provided at a treatment station where a treatment bath is placed. The jig can be lifted and lowered and can be pivoted or rotated about a horizontal axial line which extends in the direction of the length of the vehicle body. The vehicle body is transported to the treatment station by a hanger conveyor and is received by the jig. The vehicle body is put into and taken out of the treatment bath by lowering and lifting the jig and is rotated between a horizontal posture and a "lie-on-side" posture. In this apparatus, by putting the vehicle body into the treatment bath in the "lie-on-side" posture, the resistance at the time of putting it into and taking it out of the treatment bath is reduced, and the vehicle body is cleared of air trapped inside the vehicle body by inverting it after it has been put into the treatment bath.
In this kind of apparatus, the jig is rotatably supported between a pair of lifting frames which are provided on both sides of the treatment bath. The jig is arranged to be lifted by a power source for lifting the lifting frames. Another power source for rotating the jig is mounted on the lifting frame.
In this apparatus, the mechanism for lifting the jig becomes large and a driving source for rotating the jig is required in addition to a driving source for lifting and lowering the jig. This causes the overall apparatus to become complicated and expensive. While such an apparatus might be suitable for a mass production line, it is not suitable for experimental equipment or for production of a small number of products.